Added homogeneous 2D mesh; added tests of 1D and homogeneous 2D geo.

[drobnyjt]

• Opened an issue
• Referenced the relevant issue number(s) below
• Provided a description of the changes below
• Ensured all tests pass and added any necessary tests for new code

Fixes #206, #210

Description

Adds a Homogeneous 2D mesh option.

Tests

Added geometry tests for the new geometry type; tests run succesfully.

[drobnyjt]

Straight transposition of the boron nitride wire example errors out at the closest point routine; needs further investigation.

Edit: The cause of the issue seems to be when a point (x, y) is exactly on a vertex of a Polygon. Unsure of robust fix currently; will have to check geo library for options.

Edit 2: This has been fixed - an additional arm to cover the IntersectionPoint enum value had to be added. This has been addressed throughout the code where relevant, which might have been the cause of an exceptionally rare (only seen in simulations with N>1E7) bug I'd observed where, very occasionally, the code would panic with a geometry error.